Final answer:
Monocytes are agranular leukocytes that lack visible granules in their cytoplasm. They play an essential role in the immune response by differentiating into macrophages that phagocytize invading particles. The answer to the student's question is (2) Agranular.
Step-by-step explanation:
Monocytes are a type of white blood cell that are categorized as agranular leukocytes. Unlike granulocytes, which include neutrophils, eosinophils, and basophils, agranular leukocytes like monocytes and lymphocytes lack prominent granules in their cytoplasm. Monocytes circulate in the blood and lymph, and they differentiate into macrophages after moving into infected tissue, where they become key players in the immune response by phagocytizing foreign particles and damaged cells.
In the context of the question, the correct answer is (2) Agranular. Monocytes belong to the category of agranulocytes, which are white blood cells that do not contain visible cytoplasmic granules under a light microscope. Monocytes have a crucial role in both the innate and adaptive immune responses and are involved in the defense against various pathogens, including bacterial and viral infections.